Important: #97462 - Removed MSSQL supportive code¶
Support for Microsoft SQL Server (MSSQL) has been dropped as supported database system with forge#96553.
Therefore supportive code for MSSQL has been removed from Core, additionally to Align SystemEnvironment checks to changed requirements.
special handling for MSSQL platform/driver has been remove on several places
removed internal doctrine/dbal facade classes
MSSQL could not be selected during installation, but be configured manually through the database configuration. This does not work anymore, and regarding the removal of special handling code it would not be reliable. Migrate to one of the supported database system and version before upgrading to TYPO3 v12.